Recently, with the advance of sensor technologies, a sensor for acquiring a user's sleep information is under development. A technique which checks for a user's sleep state to induce a sleep in order to help a user to have a deep sleep is being actively researched by incorporating the sensor technology and an information technology (IT).
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.